1924, Iris hexagona
Addisonia page 51, plate 314, 1924
Native of the coastal southeastern United States
Family Iridaceae, Iris Family
Iris hexagona Walter, Fl. Car. 66. 1788.
Of the two species of Iris proposed by Thomas Walter and the four recorded by him from the region covered by his "Flora" Iris hexagona is the largest; in fact, it is the most robust of our eastern American species. It is a stout and rigid plant with a yellowish-green tint in the foliage, its flowers show the greatest amount of a very rich shade of purple in the perianth, and the crest of the sepal is most prominent.
Iris hexagona is confined to the southern Atlantic and Gulf coast strip, but its exact range is not yet known; from the coasts of South Carolina and Georgia it passes diagonally across northeastern Florida to near the angle of the Gulf Coast, whence it extends westward. If this plant grew further northward before the glacial period, there is no evidence that it ever attempted to regain the ground it may have lost. It seems more likely that, for some unknown reason, its ancestors took an eastward and southward course when they left the Appalachian plant reservoirs after the final submergence and uplift of the continent preceding the glacial period.
In its native haunts it demands a black silt loam, and much water, growing mostly in permanently wet ditches, in swamps, and in shallow slow-flowing streams. It is equally at home in the full sunlight or in the half shade of shrubs and trees.
In the Atlantic side of its range Iris hexagona seems to hug the coast, where it is associated with Iris Carolina, perhaps on account of the lower land where water is more abundant. Near the Gulf coast it extends further inland, for there the land is very low and flat, and the rise inland is much more gradual than along the Atlantic Ocean.
This flag is a comparatively late bloomer. The flowers are peculiar in that they last for several days without wilting. The pods of the other species inhabiting the same region are formed or ripened when the plants of Iris hexagona begin to flower, and they are often decayed and discharging their seeds when its pods are still green. A very rich and deep shade of purple is the rule in the flowers of Iris hexagona, but albino flowers have been observed.
As far as we can learn much of the material cultivated in gardens as Iris hexagona really does not represent that species. It seems that almost any large-flowered Iris from the southern Coastal Plain is distributed as "I. hexagona." The specimens from which the accompanying illustration was made, collected near Mount Pleasant, South Carolina, were sent by Agnes A. Auld in the spring of 1924.
The angle-pod blue-flag has a very stout rootstock. The leaves are stiffly erect, several together, with linear-attenuate, yellowish-green blades up to about three feet long or less, all glaucescent. The flower-stalk is stout, four feet tall or less, erect, strict or slightly zigzag, somewhat flattened, glaucous, simple or with one or more short, usually very short branches which are subtended by long foliaceous, usually elongate, bracts. The flower or flower-cluster is exceeded by the subtending bract. The pedicel is shorter than the ovary in anthesis. The hypanthium, covering the ovary, is longer than the pedicel, with six prominent ribs or angles, and six intermediate ribs. The perianth-tube is funnelform, nearly or quite a half inch long. The three sepals are remate, three and a quarter to four and a quarter inches long; the blade is oval or nearly so, rich purple, with an elevated linear coarsely hairy crest extending up from the claw, the green of the claw shading into yellow along the crest and the yellow shading into white flecks; the broad claw yellow-green within and distinctly striate-ribbed. The three petals are two and three quarters to three and a quarter inches long, narrowly spatulate, erect, the blade deep purple, often notched at the apex, the claw yellowish green at the base, whitish and lined and flecked with purple above. The stamens are about 4 cm. long, with the filament yellow and the anther linear, slightly longer than the filament. The three style-branches are broadly linear to linear-cuneate, about two inches long, greenish white and purple-tinged within. The style-appendages are scythe-shaped or some what falcate, one half to three quarters of an inch long, erose. The stigma is broadly two-lobed, with each lobe finely erose. The capsules are ovoid or oval-ovoid, one and a half to two inches long, blunt or stout-beaked, with a slight ridge or groove on each face, the angles with two lateral, elevated, often sharp ridges, all terminating in stout pedicels usually less than half their length. The seeds, borne in two rows in each carpel or cavity of the capsule or sometimes in one row in some of the cavities, are very corky, irregular from mutual pressure, pale brown, four twelfths to five twelfths of an inch in diameter.
John K. Small.
Gallery of Plates from Addisonia
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